Surprised NXWM have never considered offering a day return fare on the X51?
With the train journey taking anywhere between 22 and 32 minutes (depending on its stopping pattern), and the X51 off peak taking only 32 minutes, the bus to me offers a very viable alternative to the train!
Could be a money maker for NXWM!
Personally, I think there is no need. At £3.90 for an all day ticket, I think that is a much better option anyway. Also it provides onward journeys from Brum or Walsall. The X51 always seem to have good loads, so I think a reduced return ticket would mean less cash revenue for them as they would just be giving away cheaper fares to existing passengers who use it and pay the full £3.90 anyway.